Method and apparatus for bending glass sheets



Feb. 15, 1966 R. E. RICHARDSON 3,

METHOD AND APPARATUS FOR BENDING GLASS SHEETS Filed Sept. 18. 1964 5Sheets-Sheet 1 Feb. 15 1966 R. E. RICHARDSON 3,235,350

METHOD AND APPARATUS FOR BENDING GLASS SHEETS Filed Sept 18 1964 5Sheets-Sheet 2 Feb. 15, 1966 R. E. RICHARDSON 3,235,351}

METHOD AND APPARATUS FUR BENDING GLASS SHEETS Filed Sept. 18 1964 5Sheets-Sheet 5 Feb. 15, 1966 R. E. RICHARDSON 3,235,350

METHOD AND APPARATUS FOR BENDING GLASS SHEETS Filed Sept 18 1964 5Sheets-Sheet 4 Feb. 15, 1966 R. E. RICHARDSON 3,235,350

METHOD AND APPARATUS FOR BENDING GLASS SHEETS Filed Sept.'l8. 1964 5Sheets-Sheet 5 ATTORNEYS United States Patent 3,235,350 METHOD ANDAPPARATUS FOR BENDING GLASS SHEETS Ronald E. Richardson, Oshawa,Ontario, Canada, assignor to Pittsburgh Plate Glass Company, Pittsburgh,Pa. Filed Sept. 18, 1964, Ser. No. 398,835

Qlaims priority, application (lanada, Oct. 31, 1960,

810,043 6 Claims. (Cl. 65-107) This application is acontinuation-in-part of the pre viously filed application Serial No.96,846, filed March 20, 1961, and now abandoned. This invention relatesto improvements in the construction of concave, multipart, skeleton typemolds of the type having a fixed center section and an end sectionpivotally secured to opposed ends thereof and particularly to providingin such molds intermediate or ancillary supports rigidly fixed to thecenter section and projecting therefrom into the zones of the mold endsections.

Skeletonized molds are well known in the art wherein the pivotal endsections are biased, usually by means of weights, so that they tend tomove from an open position to a closed position. Initially, a flat, coldglass sheet is placed on a mold with the end sections pivoted to an openposition where it is held by the weight of the glass sheet. In thisposition the glass sheet is supported at relatively few spaced points,two of which are constituted by the extreme end tips of the mold and/orby ancillary supporting devices located adjacent such tips.

Upon heating of the glass to bending temperature the glass softens withthe result that the downward force exerted by the glass sheet on the endsections diminishes and the end sections move upwardly towards theirclosed positions. At the completion of the bending operation when ttheend sections are fully closed, they serve to define with the fixed mainsection a continuous concave shaping surface adapted to impart thedesired curvature to the glass sheet.

Modern trends in automobile design call for the use of increasinglylarger glass sheets in Windshields and rear windows and for curvaturesof increasing complexity. The production of these large sheets ofcomplex curvature on skeleton type molding surfaces involves somedifficulty. For example, the glass shaping rails constituting theportion of the shaping surface presented by the center section of themold frequently have an upward curvature at the parts thereof adjacentto the glass shaping rails of the end sections of the mold. Thelongitudinal extremities of the center section rails are thereforeraised above the level of the remainder of these rails. As a result,when the glass sags longitudinally during the bending towards theshaping surface the first points of contact of the glass sheet with theshaping surface (other than the points of initial support mentionedabove) are at these raised extremities of the center section railscommonly referred to as cut points. If the glass remains in contact withthese out points for an appreciable length of time, kinking of the sheetis liable to occur. Similarly, kinking of the tips of the sheet canresult from the force exerted thereon during the bending operation whenthe sheet is solely or primarily supported by the tips of the endsections or the mentioned ancillary supports at such tips duringbending.

Another difiieulty arises from the fact that the design of automobileWindshields and rear windows now frequently involves the provision ofcurvature transversely of the length of the glass. This results in thenecessity to use a skeleton type mold having some portions of itsshaping surface much lower than others and hence farther removed fromthe glass sheet during the initial stages of the bending operation.Since the metal of which the mold is constructed exercises a chillingeffect on glass located adjacent thereto, there is thus a tendency forunequal heating between the two sides of the glass sheet with the resultthat sagging tends to occur at the side where the shaping surface isfarthest removed from the glass. This problem is particularlyencountered when forming sheets having a curvature containing a compoundbend with a pronounced transverse curvature.

It is an object of the present invention to provide a mold constructionby means of which kinking of the glass sheet at the mold tips or at thecut points can be minimized.

It is a further object of the invention to provide a mold constructionby means of which undesirable sagging of the glass sheet at portionsthereof which are to be received by a part of the shaping surfacefarther removed from the sheet prior to bending than other portions ofthe shaping surface can be minimized.

In one aspect of the invention, there is provided a concave glassbending mold of the multi-part, skeleton type movable between an openposition for receiving a sheet of flat glass thereon and a closedposition peripherally defining a curved shaping surface with which theglass sheet is to conform after bending, said mold includes a centermold section comprising a first pair of spaced, substantially parallelglass-shaping rails defining a first portion of said shaping surface andhaving the longitudinal extremities thereof disposed above the level ofother portions of said rail, an end mold section pivotally connected tosaid center mold section at opposed ends thereof for pivotal movementbetween an open position and a closed position, said end mold sectionseach including a second glass-shaping rail defining a second portion ofsaid shaping surface lying contiguous with the ends of the rails of saidfirst portion when the mold is in the closed position, and a glassintermediate support member rigidly secured to said center mold sectionand projecting therefrom into the area of at least one of said endsections, said supporting member having an upper arcuately shapedsurface disposed within the area of the end section defining a pluralityof successive support points for the glass sheet during movement of themold from the open to the closed position.

The invention will be described by way of illustration and withoutlimitation with reference to the accompanying drawings wherein:

FIG. 1 is a plan view of half of a skeleton type concave glass bendingmold, only half of the mold being illustrated since the mold issymmetrical.

FIG. 2 is a side View of the mold of FIG. 1,

FIG. 3 is an end view of the mold of FIG. 1,

FIG. 4 is a side view of the mold of FIG. 1 with the mold parts somewhatdifferently disposed than in FIG. 2,

FIG. 5 is a side view of the mold of FIG. 1 similar to that of FIG. 4when bending of a glass sheet thereon has been about half completed,

FIG. 6 is a view similar to that of FIG. 5 after completion of thebending operation,

FIG. 7 illustrates a modification of the embodiment of FIG. 1,

FIG. 8 illustrates diagrammatically the modes of operation of the moldof FIGS. 1 and 7,

FIG. 9 shows a further modification of the mold of FIG. 1,

FIG. 10 is a plan view of a detail of FIG. 9,

FIGS. 11 and 12 illustrate further modifications of the embodiment ofFIG. 1 and FIGS. '13 and 14 are vertical side elevational views of oneend of one side rail on the fixed portion of the mold having an armextending therefrom with a short portion' adjacent the end thereofforming an intermediate support. Shown in the drawings is a skeletontype, sectionalized mold including a main central fixed section 1 havinga pair of movable end sections 2 pivotally secured thereto at opposedends thereof, only one such end mold section being visible in thedrawing.

The main mold section 1 includes a pair of spaced shaping side rails 3interconnected by bracing members 4. The bracing provided by the bracingmembers'4 is reinforced by vertically disposed upstanding plates 5extending transversely across the mold and secured at their ends to themain side rails 3 and by bars 6 extending diagonally across the mold andsecured to the plates 5.

The end mold section 2 includes a curved end shaping rail 7, a mainbracing member 8 and subsidiary bracing members 9. To each end of theend rail 7 there is secured by struts 10 a plate 11 provided with a keyhole slot 12. At each side of the mold there is mounted a grooved pivotpin 14 supported on a rod 15 secured to and extending upwardly from amold supporting frame 16 to which the side bars 3 are connected bymembers 17. The keyhole slots 12 are formed with upper portions having adiameter only slightly greater than the inner diameter of the grooves inthe pivot pins 14 and less than the diameter of these pins, and withlower portions of a diameter greater than that of the pivot pins 14. Bypassage of the pivot pins 14 into the lower portions of the slots 12,the edges of the upper portions of the slots 12 may be lowered intoengagement with the grooves of the pivot pins 14 thereby to mount theend section 2 for pivotal movement relative to the main mold portion 1.Arms 19 carrying counterweights 20 are secured to the plates 11 and tendto urge the outer end of the end mold sections 2 upwardly from a spreadmold position wherein the longitudinal outer extremities of each endrail 7 bears against the under surface and thereby support a flat glasssheet towards a closed position where, as shown in FIG. 6, the ends ofthe curved end rail 7 forms a contiguous smooth continuation of the siderails 3.

The mold also includes curved intermediate support rails 22 and 23referred commonly to as roll bars each rigidly secured to the main moldsection, and extending longitudinally outwardly therefrom into the zoneof the end section and slightly laterally inboard of the pivotal pathtraversed by the inner ends of end rails 7. The support rails aresecured to the side rails 3. However, they could also conveniently besecured to other portions of the fixed mold structure. The support rail22 is braced by bracing members 24 extending between the rail 22 and theoutermost plate 5 and the rail 23 is braced by a bracing member 25extending between the rail 23 and the outermost plate 5. Each of thesupport rails 22 and 23 has a convex upper surface, the most part ofwhich is above the level of the longitudinal extremity or cut point 26of the associated side rail 3. iImmediately adjacent the cut point 26however the upper edges of the intermediate support rails 22 and 23 arebelow the level of the cut points 26. The upper edges of such rails arefixed in position to the side rails 3 and occupy a position above theupper edges of the inner ends of end rails 7 when the end section 2occupies its flat glass supporting position depicted in FIG. 4. Thisposition is below the upper edges of the inner ends of the end rails 7when the end rails are pivoted to the closed mold position depicted inFIG. 6.

In FIGS. 2 and 3 the mold is shown with the end section 2 helddownwardly away from the position it assumes at the time that a flatglass sheet is loaded onto the mold. This is merely to indicate moreclearly the disposition of the immediate support rails 22 and 23 and themanner in which a glass sheet 28 rests upon these rails when firstloaded onto the open mold.

FIG. 4 illustrates the relationship between the glass sheet and the moldimmediately after loading of the sheet 28 onto the mold with the endsection 2 being urged upwardly against the sheet by the counterweightedarms 19.

In this position the glass sheet is supported partly by the: tip of theend section 2 and partly by some portion along. the upper edge of theintermediate support rails 22 and? 23. This constitutes a three-pointsupport at each end? of the mold in contrast to the single-point supportwhich would exist in the absence of the intermediate support rails 22and 23.

FIG. 5 shows the nature of the support afforded the sheet part waythrough the bending operation. Upon introduction of the mold togetherwith the glass sheet into a bending lehr where the glass is heated tobending temperature, the sheet 28 softens. Under the influence of thecounterweighted arms 19 the end section 2 of the mold pivots upwardlytowards its closed position and when such movement has been completed,the glass has been bent to the prescribed curvature defined by theconcave shaping surface of the mold in the closed position. It will benoted that the glass sheet 28 is still supported at its tip by the tipof the end section 2. It is also still supported by the intermediatesupport rails 22 and 23 but the points of support provided by theserails are located nearer to the cut points 26 than are the initialpoints of support shown in FIG. 2. With progressive bending of the sheet28 towards final contact with the shaping surface of the closed mold thepoints of support provided by the intermediate support rails 22 and 23move progressively inwardly towards the cut points 26. Since the cutpoints 26 are above the level of the adjacent portions of theintermediate support rails 22 and 23 the glass eventually comes to restupon these cut points and moves out of contact taltogether with therails 22 and 23. It is then supported by the cut points 26 and the tipof the end section 2. This does not occur however until the bendingoperation has been almost completed so that the glass is in contact withthe cut point for only a short time before the end sections of the moldhave reached their closed positions and have completed the continuousshaping surface defined by the side rails 3 and the curved end rail 7when the mold is in the closed position.

In molds of the prior art not provided with intermediate supportdevices, according to this invention, as exemplified by support rails 22and 23, the glass comes into contact with the cut points of the centersection of the mold a considerable time before the bending operation hasfully completed. As indicated above, this frequently causes kinking ofthe glass in the regions bearing on the cut points. Also before theglass sheet has sagged to a sufiicient extent that it contacts the cutpoints and is supported thereby the full weight, or much of the weight,of the sheet is supported at its tips with the result that kinking mayoccur adjacent the tips of the sheet.

By contrast, in the mold described above with reference to FIGS. 1 to 6,each of the support rails 22 and 23 provides an intermediate supportingsurface with which the surface of the glass sheet is in rolling contactfrom the beginning until almost to the end of the bending operation. Inother words each of the rails 22 and 23 furnishes a continuous line ofintermediate support points successively in contact with the glassduring bending. This reduces the load at the tips of the sheet, therebyminimizing tip kinking, while at the same time keeping the glass sheetoff the cut points 26 until so near to the end of the bending operationthat the cut points bear against the glass for an insufficient length oftime to cause appreciable kinking.

Furthermore, it will be seen from FIG. 2 that the intermediate supportrail 23 bears against a side of the sheet 28 which, at the beginning ofthe bending operation, is farther separated from the portion of the endrail 7 lying beneath it than is the other side of the sheet 28. Thisunequal separation between the sheet 28 and the opposite sides of theend rail 7 is dictated by the nature of the curvature being imparted tothe sheet. As a result of it the end rail 7 exercises a greater chillingefieet on one side of the sheet than the other during the bendingoperation.

This can give rise to unequal heating of the two sides of the sheet withthe consequence that the side of the sheet farthest separated from theend rail '7 sags downwardly more than is tolerable in order to obtain asatisfactorily bent sheet. Such undesirable sagging is however minimizedin the mold described because the tendency for it to occur iscounteracted by the presence of the support rail 23. The latter railprovides physical support for the portion of the sheet which would tendto sag and also exercise a chilling effect thereon.

FIG. 7 shows a modification of the mould of FIG. 1 wherein anintermediate support rail 230, corresponding to the intermediate supportrail 23 of FIG. 1, is mounted on a pin 30 secured to the main side rail3 so as to be pivotable relative to the side rail. An arm 31 providedwith counterweights 32 issecur-ed to the inner end of the intermediatesupport rail 23a and serves to urge the rail 23a upwardly against thesheet 28. This has the effect of still further relieving the load on thetip of the glass sheet where it bears against the tip of the end ofsection 2. During the bending operation the intermediate support rail23a is continuously in rolling contact with the sheet 28 and provides aline of successive support points during the bending operation untilimmediately before the end section 2 has attained its closed positionand the desired curvature has been imparted to the sheet 28. The inter-.mediate support rail 23a: is prevented from contacting the glass sheet28 when the mould is in the fully closed position in that the arm 31contacts a fixed stop (not shown) shortly before attainment of theclosed position of the mould thereby preventing further upward movementof the rail 23a.

FIG. 8 indicates diagrammatically the contour of the line of spacedsupport point provided by the intermediate support rail 23 of FIG. 1 andby the intermediate support rail 23a of FIG. 7 during the bendingoperation. The broken line A represents the fixed position of theintermediate support rail 23 or the initial position of the intermediatesupport rail 23:: or immediately after loading of the glass sheet 28onto the mould. In the case of the intermediate support rail 23 thepoint of support of the glass sheet by the rail moves downwardly alongthe broken line A during the bending operation as indicated by a seriesof circles representing a few of the infinite number of successivesupport points. In the case of the intermediate support rail 23a of FIG.7 the positions of the upper edge of this rail at three successivestages during the bending operation is indicated by the broken lines B,C and D. Four of the infinite number of successive support pointsprovided by the intermediate support rail 23a for the sheet 28 duringthe bending operation is indicated by a series of crosses each of whichlies on one of the dotted lines A, B, C and D. It will be observed thatthe use of the pivoted intermediate support rail 23a makes it possibleto provide an intermediate supporting surface of a highly convexnatur-eso convex that a fixed rail having the same contour would notprovide satisfactory rolling contact throughout the bending operationbecause its highest point would be fairly close to the cut point 26 ofthe center section 3. The provision of a line of support points havingsuch a pronounced convex curvature may be of considerable advantage whenforming some of the highly complicated bends now required in theproduction of automobile glass.

FIG. 9 shows a further modification of the mold of FIG. 1 wherein anintermediate support rail 23b corresponding to the intermediate supportrail 23 of the mold of FIG. 1, is secured to the side rail 3 in suchmanner that the upper convex surface of the intermediate support rail23b is contiguous with the upper surface of the side rail 3. As aresult, the sheet 28 remains in rolling contact with the intermediatesupport rail 23b throughout the whole of the bending operation and isstill in contact therewith after bending has been completed. This isclearly desirable in that such a construction prevents the sheet 28 fromever coming into contact with the cut points 26 of the side rails 3. Thereason that such a construction is not adopted in the mold of FIG. 1 isthat it would result in an effective thickening of the shaping surfacewithin the regions where the side rail 3, the end rail 7 and theintermediate support rail 23 are in close proximity to one another,i.e., in the region of overlap between the side rail 3 and theintermediate support rail 23 and in the region where the end rail 7 liesclosely adjacent to the intermediate support rail 23. The shapingsurface would therefore have an increased thermal capacity at theseregions which would give rise to a shadowing effect. This difficulty isovercome in the construction of FIG. 9 in that, as shown in FIG. 10(which is a plan view of FIG. 9), the outer end of the side rail 3b andthe inner end of the end rail 7b are diminished in thickness in theregion of overlap between the side rail 3b and the intermediate supportrail 23b so that they together have a combined thickness equal to thatof the general thickness of the side rail 3. Also, in the region wherethe end rail 7 lies closely adjacent the intermediate support rail 23bthe thickness of the end rail 7 is reduced so that there is noappreciable effective thickening of the shaping surface in that region.The shadowing effect mentioned above is thereby substantially eliminatedand the advantage of having the intermediate support rail in rollingcontact with the glass sheet 28 throughout the whole of the bendingoperation can be obtained.

In the embodiments of mold construction described above, the rails 22,23, 23a and 2312 are all located inboard of the mold. In fact, inintermediate support all such embodiments the intermediate support railsfurther are located effectively wholly within the zone of the endsection. It is however possible to mount these rails outboard of themold provided that the edge of the glass sheet extends for a sufiicientdistance over the edge of the shaping surface presented by the mold forthe sheet to remain in rolling contact with the support rail at leastuntil near the completion of the bending operation.

Furthermore, although FIGS. 7 and 9 illustrate modifications of only theintermediate support rail 23 it will be evident that similarmodifications can be made to the intermediate support rail 22. In someinstances it may bedesirable to have a fixed intermediate support railat one side of the mould and a pivoted, counterweighted intermediatesupport rail at the other side of the mold.

Another possibility within the scope of the invention is the provisionof a single intermediate support rail. This may be disposed at one sideonly of the mold or, if the bracing of the end section permits, mayextend all the,

tion of a glass sheet having a highly complex bend it ispossible that aglass supporting member with a concave upper surface could usefully beemployed provided that the radius of curvature of the upper surface ofthe glass supporting member if substantially greater than that of theconcave shaping surface of the mold so that the upper surface of thesupport rails 22, 23, 23a and 23b have a contour that follows the lineof contact produced by sagging the glass sheet inwardly of the portionlifted upwardly on the mold extremity as the bending operation takesplace. Generically the shape of the upper surface of the intermediatesupport rail may be referred to as being arcuate. Such shaping causeseffectively rolling contact between the glass during bending and theupper surface of the intermediate support rail. Also it is sometimesdesirable to use glass intermediate supporting members, the upper edgesof which are provided with both concave and convex portions or includefiat portions. For example, FIG. 11 shows an intermediate support rail230 the upper surface of which has a convex portion 231/, a concaveportion 23v and a flat portion 23w while FIG. 12 shows an intermediatesupport rail 23d the upper surface of which has a first convex portion23x, a concave portion 23y and a second convex portion 23z. Suchcomposite curvatures are often of assistance when it is desired toprovide a plurality of support points for a glass sheet to which acompound bend is being imparted.

The intermediate support rails 22, 23, 23a and 23b all serve to providea continuous line of successive support points for the glass sheetduring movement of the mold from the open to the closed condition sincethey each have a smoothly convex upper surface. This is not necessarilytrue of the support rails 23c and 23d. The line of successive supportpoints provided by these latter support rails may be discontinuous,depending on the characteristics of the mould to which the rails arefitted. Such discontinuity does not prevent the advantages of theinvention from being obtained. It is merely necessary that a pluralityof successive support points be provided during the movement of themould from the open to the closed position.

The intermediate supports described are effectively in rolling contactwith the lower surface of the glass sheet during bending. Such describedintermediate supports are also referred to as roll bars and since theyextend over a considerable length they may be referred to as long rollbars. In FIGURES 13 and 14 there is shown short roll bars wherein theintermediate support is relatively short in length and is in spacedrelation with respect to the cut oint.

p Referring to FIGS. 13 and 14 shown therein is a side rail 3 having abar 40 rigidly secured thereto and projecting outwardly from the cutpoint 26. The bar 40 terminates in an enlarged outer end portion 41having an upper arcuate edge portion 42 to be in rolling contact withthe glass sheet during the bending thereof and provide an intermediatesupport therefor. In FIG. 13 the edge portion 42 is an integral part ofthe bar 40 while in FIG. 14 it consists of a separate portion addedthereto and the latter is substantially relatively shorter than theformer. In the particular embodiment illustrated in FIGS. 13 and 14, thelength of the roll bar in contact with the glass is approximately onehalf inch. This may be termed a relatively short roll bar in that thelength of contact in the other embodiments is approximately nine inches.This latter bar, accordingly, may be referred to as a relatively longroll bar. The upper surface for supporting glass in any event is convexand such shape minimizes the time of dwell of the soft glass on eachpoint of the intermediate support as the glass sheet moves from the flatto the curved configuration. By minimizing the time of support at anyone point, penetration of the intermediate support into the softenedglass is reduced.

The various embodiments of the invention have been described in terms ofa mould having a fixed center section. It is inherent in the presentinvention that the intermediate support rails 22, 23, 23a, 23b, 23c, and42, which serve as intermediate support members for contacting thebottom surface of the glass sheet longitudinally outwardly of the centermould section and longitudinally inwardly of the mould longitudinalextremities; i.e., in the zone of the end sections, may be attached tocenter section rails of a mould whose center section is not fixed to asupport frame, but whose center section is permitted to move verticallywith respect to the mould support frame as the pivoted end sectionoscillate between their open position and their closed position.

The important feature of all the embodiments illustrated and of thepresent invention in general is that the upper surface of the glassintermediate supporting members 22, 23 etc., be located above theshaping surface of the adjacent pivoted end sections 7 when the latteroccupy their open position and that each glass intermediate supportmember has its upper surface below the shaping surface of its adjacentend mould section 7 when the latter is pivoted into the closed mouldposition with each successive point along said upper surface thatcontacts the bottom surface of the glass sheet during its bendinglocated longitudinally inwardly of the preceding glass contacting point.

The above description of various embodiments according to the presentinvention has been made for the purpose of illustration rather thanlimitation. Reference to the latter may be obtained by studying theclaimed subject matter Which follows.

I claim:

1. A concave glass bending mold of the multi-part skeleton type movablebetween an open position for receiving a sheet of fiat glass thereon anda closed position peripherally defining a curved shaping surface withwhich the glass sheet is to conform after bending, said mold including amain mold section having a first glassshaping rail defining a firstportion of said shaping surface and having a longitudinal extremitydisposed above the level of other portions of said rail, an end moldsection pivotally connected to said main mold section for movementbetwen an open position and a closed position, said end mold sectionincluding a second glassshaping rail defining a second portion of saidshaping surface lying contiguous with said first portion when the moldis in the closed position, and an intermediate glass supporting memberrigidly secured to said main mold section, said glass intermediatesupporting member having an elongated, arcuate, upper surface disposedwithin the zone defined by the end mold section and including aplurality of support points located longitudinally inwardly of oneanother at positions occupied and sequentially alternately engaged anddisengaged by the bottom surface of the glass sheet during bendingthereof in movement of the mold from the open to the closed position.

2. A concave mold as defined in claim 1 wherein the upper surface of theintermediate supporting member is relatively short and disposed withinthe zone of the end mold section and spaced a predetermined distancefrom the center section.

3. A concave glass bending mold according to claim 1 wherein the uppersurface of said glass-supporting member is constructed to defined acontinuous line of successive support points for the glass sheet duringmovement of the mold from the open to the closed position.

4. A concave glass bending mold of the multi-part skeleton type movablebetween an open end position for receiving a sheet of flat glass thereonand a closed position peripherally defining a curved shaping surfacewith which the glass sheet is to conform after bending, said moldincluding a main mold section comprising first and second laterallyspaced, generally parallel, glassshaping rails each having twolongitudinal extremities disposed above the level of other portions ofthe rail, an end mold section situated outwardly of said main moldsection at opposite ends thereof, said end mold sections includingrespectively a third and fourth glass shaping rail, said end moldsections co-operating with said main mold section in the closed positionof the mold to form a substantially continuous glass-shaping surfaceextending between an end of said third glassshaping rail and an end ofone of said first and second glass-shaping rails and between an end ofsaid fourth glass-shaping rail and the other of said first and secondglass-shaping rails, a first glass intermediate supporting memberextending longitudinally outwardly and upwardly from a longitudinalextremity of said first glass-shaping rail at one end of said main moldsection, a second glass intermediate supporting member extendinglongitudinally outwardly and upwardly from one of said glass-shapingrails at the other end of said main mold section, each of said glassintermediate supporting members having an elongated upper arcuatesurface including a plurality of support points located longitudinallyinwardly of one another at positions occupied by the bottom surface ofsaid glass sheet during bending thereto in movement of the mold from theopen to the closed position.

5. In the method of bending a glass sheet into conformity with a shapingsurface of concave elevation by a combination of heat sagging and upwardlifting of a longitudinal extremity ofthe sheet wherein the glass sheetbefore bending is initially supported adjacent and intermediate itslongitudinal extremities in an initial plane of support, the improvementcomprising engaging the glass sheet intermediate its longitudinalextremities at an initial support point disposed along the initial planeof support for the glass and lifting said longitudinal extremities ofthe glass sheet above said initial plane of support while alternatelyengaging and disengaging the glass sheet intermediate its longitudinalextremities on points of support successively disposed longitudinallyinwardly of one another before the entire length of the glass sheet isdeposited on said shaping surface of concave elevation.

6. In a method of bending a glass sheet wherein the sheet is exposed tobending temperature while supported adjacent the longitudinalextremities of the sheet, the improvement comprising providingadditional support for the sheet during bending thereof at a pluralityof support points which are successively brought alternately into andout of contact with the sheet during the bending thereof, each of saidsupport points being disposed longitudinally inwardly (if any of saidplurality of support points previously in contact with said sheet.

References Cited by the Examiner UNITED STATES PATENTS DONALL H.SYLVESTER, Primary Examiner.

1. A CONCAVE GLASS BENDING MOLD OF THE MULTI-PART SKELETON TYPE MOVABLEBETWEEN AN OPEN POSITION FOR RECEIVING A SHEET OF FLAT GLASS THEREON ANDA CLOSED POSITION PERIPHERALLY DEFINING A CURVED HAPING SURFACE WITHWHICH THE GLASS SHEET IS TO CONFORM AFTER BENDING, SAID MOLD INCLUDING AMAIN MOLD SECTION HAVING A FIRST GLASSSHAPING RAIL DEFINING A FIRSTPORTION OF SAID SHAPING SURFACE AND HAVING A LONGITUDINAL EXTREMITYDISPOSED ABOVE THE LEVEL OF OTHER PORTIONS OF SAID RAIL, AN END MOLDSECTION PIVOTALLY CONNECTED TO SAID MAIN MOLD SECTION FOR MOVEMENTBETWEEN AN OPEN POSITION AND A CLOSED POSITION, SAID END MOLD SECTIONINCLUDING A SECOND GLASSSHAPING RAIL DEFINING A SECOND PORTION OF SAIDSHAPING SURFACE LYING CONTIGUOUS WITH SAID FIRST PORTION WHEN THE MOLDIS IN THE CLOSED POSITION, AND AN INTERMEDIATE GLASS SUPPORTING MEMBERRIGIDLY SECURED TO SAID MAIN MOLD SECTION, SAID GLASS INTERMEDIATESUPPORTING MEMBER HAVING AN ELONGATED ARCUATE UPPER SURFACE DISPOSEDWITHIN THE ZONE DEFINED B THE END MOLD SECTION ARE INCLUDNG A PLURALITYOF SUPPORT POINTS LOCATED LONGITUDINALLY INWARDLY OF ONE ANOTHER ATPOSITIONS OCCUPIED AND SEQUENTIALLY ALTERNATELY ENGAGED AND DISENGAGEDBY THE BOTTOM SURFACE OF THE GLASS SHEET DURING BENDING THEREOF INMOVEMENT OF THE MOLD FROM THE OPEN TO THE CLOSED POSITION.
 5. IN THEMETHOD OF BENDING GLASS SHEET INTO CONFORMITY WITH A SHAPING SURFACE OFCONCAVE ELEVATION BY A COMBINATION OF HEAT SAGGING AND UPWARD LIFTING OFA LONGITUDINAL EXTREMITY OF THE SHEET WHEREIN THE GLASS SHEET BEFOREBENDING IS INITIALLY SUPPORTED ADJACENT AND INTERMEDIATE ITSLONGITUDINAL EXTREMITIES IN AN INITIAL PLANE OF SUPPORT, THE IMPROVEMENTCOMPRISING ENGAGING THE GLASS SHEET INTERMEDIATE ITS LONGITUDINALEXTREMITIES AT AN INITIAL SUPPORT POINT DISPOSED ALONG THE INITIAL PLANEOF SUPPORT FOR THE GLASS AND LIFTING SAID LONGITUDINAL EXTREMITIES OFTHE GLASS SHEET ABOVE SAID INITIAL PLANE OF SUPPORT WHILE ALTERNATELYENGAGING AND DISENGAGING THE GLASS SHEET INTERMEDIATE ITS LONGITUDINALEXTREMITIES ON POINTS OF SUPPORT SUCCESSIVELY DISPOSED LONGITUDINALLYINWARDLY OF ONE ANOTHER BEFORE THE ENTIRE LENGTH OF THE GLASS SHEET ISDEPOSITED ON SAID SHAPING SURFCE OF CONCAVE ELEVATION.